1. Field of the Invention
The invention relates to a packing material and to a pack for active substance patches, especially for transdermal therapeutic systems. The invention further embraces processes for producing such a packing material and such a pack, and to a process for packaging active substance patches using the packing materials of the invention.
2. Description of the Related Art
Transdermal therapeutic systems (TTS) are patches comprising active substances or drugs and have been introduced on the market as such. Because of their ability to provide controllable release of pharmacologically active substances to the body via the skin over a prolonged period of time, they possess a range of advantages over other drug forms.
TTS generally possess pressure-sensitively adhering layers which are intended to enable their attachment to the skin. During storage and before application to the skin, these layers are covered on the adhesive side with a removable protective layer. However, this layer is unable to prevent, or to prevent completely, the emergence of small amounts of the pressure-sensitively adhering material, especially at the side edge regions, in the course of storage, as a consequence of the “cold flow”—and to an increased extent at slightly raised temperatures. One consequence of this may be that the TTS stick to the inside of their surrounding packaging, which in turn complicates handling on removal from the packaging and which may cause a TTS to be destroyed. This not only gives rise to avoidable costs but also impairs the acceptance of these drug forms among users.
Further requirements on packaging suitable for TTS arise from the fact that TTS may also comprise volatile ingredients, e.g., volatile active substances or excipients, whose release to the environment must be prevented. It is likewise necessary to rule out reaction between ingredients of the TTS and the packaging material, and vice versa.
For these reasons, TTS are normally packaged in what are known as sealed bags, which are composed of a double ply of a laminate. Said laminate has at least two, but generally more, layers.
Commonly, the inward-facing layer is sealable. It is very common in the packaging of TTS to carry out edge sealing using heat, producing a virtually homogeneous bond between the sealing layers of the upper and lower sealing laminate. An alternative possibility, in principle, is that of cold sealing, using for example moisture, solvents or other contact auxiliaries, e.g. known cold sealing compositions.
In order to bring about the required imperviousness toward losses of active substances or other ingredients, some of which are volatile, the customary packing materials used for packaging TTS are additionally furnished with a barrier layer. In general, this is the next innermost layer after the sealing layer. The barrier layer may be composed, for example, of a continuous metal layer (usually aluminum), although in principle a diffusion-type polymer material such as polyethylene terephthalate, for example, may be suitable.
In addition, the packages may be provided with further layers, generally attached on the outside, which may be composed, for example, of paper or of polymer films. These layers are, for example, for enhanced printability, for security against unwanted destruction by tearing (child safety), or an esthetically appealing design.
One disadvantage of the packs known from the prior art is the absence of any devices which prevent the full or partial sticking of the TTS present in the pack to the inside of the pack or of the packing material. This is a problem on account of the fact that there are a number of TTS or active substance patches which, owing to their composition or ingredients, are especially sensitive and tend to stick to the packing material.
It is true that sticking on the inside of the pack can in principle be prevented by providing the inside with a silicone coating. However, because silicones are not sealable, it is necessary during the production process to ensure that the edges of the packing material, intended for sealing, are not siliconized; in other words, these packing materials are provided only with a partial, noncontinuous siliconization. On the one hand this requires a corresponding production process, which produces silicon-free edges, and on the other hand it has the consequence that, when packing the TTS, precise positioning on the abhesively coated area of the packing material to be sealed is necessary.